A bio-blender and pump have been installed at the company's Kilmarnock depot as part of a £75,000 investment.

Buses at the site will run on a 40 per cent biofuel and 60 per cent diesel mix compared to the five per cent and 95 per cent mix common across the rest of the fleet.

Previously the Kilmarnock depot trialled nine vehicles which ran on 100 per cent biofuel made from used cooking oil and other food industry by-products.

That project, which allowed people to exchange used cooking oil for discounted travel, has saved 2450 tonnes of carbon since it was launched in 2007.

Les Warneford, managing director of Stagecoach UK Bus, said: "We have had great success in Kilmarnock with the bio-buses which have helped us reduce our own carbon footprint and attract more people on to greener transport.

"The installation of this bio-blender means the rest of the vehicles at the depot can now run on up to 40 per cent biofuel, making it one of the greenest bus fleets in the country.

"We are working hard to become a more sustainable business by introducing new technology and trialling new ideas."

Argent Energy advised Stagecoach on the project with the blender supplied by Fuel Additive Technology Biofuels with the pump manufactured by Solution Specialists.